Marine - Iron

ODST - Silver

I've been wondering about that too. From the trailer, as far as things like armor/weapon/architect design we can look at a few different things: marines armour and weapons, Chief's armour, warthog, and the beam emitters.

In my opinion this is what each looks like to me:Marine armour: hybridMarine weapon: modernChief: hybrid, heavier on the classic sideWarthog: modernBeam emitter: modern

Based on what we've seen so far I think it's looking to be a good mix.